qed: Add basic L2 interface

This patch adds a public API for a network driver to work on top of QED.
The interface itself is very minimal - it's mostly infrastructure, as the
only content it has after this patch is a query for HW-based information
required for the creation of a network interface [I.e., no actual
protocol-specific configurations are supported].

Signed-off-by: Manish Chopra <Manish.Chopra@qlogic.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>